Gas turbine engines typically include a compressor that delivers compressed air to a combustor in which the compressed air is mixed with fuel and burned. The rapidly expanding products of combustion move through turbine blades causing them to rotate a shaft which provides rotative force to propeller or fan blades. Turbine rotors typically include a rotor disk and a plurality of circumferentially spaced removable turbine blades. Since the rotor disk and the turbine blades are subject to extreme temperatures, cooling air is typically delivered to these components to cool them.
Cooling air may be delivered from a central location to the rotor disk and then radially outwardly to internal passages within each turbine blades.
To seal cooling passages along the rotor disk, cover plates are typically attached to the rotor disk. Cover plates typically follow the contour of the disk to create a boundary layer effect that pumps cooling air from the central location to the radially outward location while the cover plate and rotor disk rotate.